大温差循环作用下混凝土温度响应及损伤模拟

Simulation on Temperature Response and Damage of Concrete under Large Temperature Difference Cycling

通过数值模拟和试验相结合的方法,建立了混凝土三维球体随机骨料模型,利用有限元软件分析了温度响应和损伤积累过程,并通过大温差循环试验验证了模拟结果.结果表明:随着温差循环次数的增加,混凝土导热性能变差,温度梯度呈增大趋势;骨料与砂浆界面处产生较大拉应力,损伤由界面开始产生;每次循环的升温过程拉应力增大,使得损伤逐渐积累并从界面向基体扩展,最终损伤区域连通;温度响应和静弹性模量损失率模拟结果与试验测定值吻合良好,数值模拟方法合理有效.

By combination of numerical simulation and experiment,a three‑dimensional spherical random aggregate model of concrete was established.The finite element software was used to analyse the temperature response and damage accumulation process.The simulation results were verified by the large temperature difference cycling test.The results show that with the increase of temperature difference cycling times,the thermal conductivity of concrete becomes worse and the temperature gradient increases.Large tensile stress is generated at the interface between aggregate and mortar,and the damage starts from the interface.The tensile stress increases in the heating process of each cycle,with the result that the damage gradually accumulate and expand from the interface to the matrix,and at last the damage area is connected.The simulation results of temperature response and static elastic modulus loss rate are in good agreement with the experimental values.